Good little study about how Finasteride impacts 5AR activity, and how/what they test to evaluate 5AR activity. Includes graphs.
Show this to a doc next time they claim you can’t test for 5AR activity.
Laboratory Monitoring of Androgenic Activity in Benign Prostate Hypertrophy Treated with a 5a-Reductase Inhibitor:
clinchem.org/cgi/reprint/38/7/1304
"androsterone/etiocholanolone (A/B) ratio in urine as a measure of 5a-reductase activity."
This measure was used previously by Zumoff et al. (5) to show variations in metabolism of testosterone according to age and sex: the mean A/E ratio for men ages 14-45 years was -1.5 but fell to 1.0 or even slightly lower in elderly men (ages 69-87 years).
Because the analytical result is expressed as a ratio, absolute values are not required and random sampling of urine is sufficient for assessing the ratio of 5a-/5b-reductase activity.
Here is another example of how to measure 5AR activity:
Plasma androsterone/epiandrosterone sulfates as markers of 5α-reductase activity: Effect of finasteride in normal men
sciencedirect.com/science?_o … 08b8a30973
Plasma androsterone/epiandrosterone sulfates, dehydroepiandrosterone sulfate, dihydrotestosterone, testosterone, androstenedione, and cortisol were measured in three normal adult men before and following finasteride administration (5 mg/day).
Plasma androsterone/epiandrosterone sulfates and dihydrotestosterone declined in parallel to 50% of basal levels with little change in either dehydroepiandrosterone sulfate, cortisol, or androstenedione.
The results suggest that the direct measurement of plasma androsterone/epiandrosterone sulfates by enzyme-linked immunosorbent assay provide similar information to plasma dihydrotestosterone and therefore provide a simple alternative for the assessment of 5α-reductase activity.